1893. EVOLUTIONVIN THE GUIANA FOREST. 39 
he found himself lost in the forest. The perspiration streams from 
the new-comer, and unless he is enthusiastic in pursuit of his hobby 
he is glad to find himself again on the river. Where the land is low, 
pools of ruddy-brown water occupy the hollows between the im- 
mense buttresses of every tree, while here and there small streams 
wind in and out among them. The fallen leaves and other débris 
form an oozy kind of peat, obviously giving colour to the water, which 
is the same in almost every creek and river in Guiana. 
It is generally considered that the forest is unhealthy for man. 
Residents along river banks suffer more or less from intermittent 
fevers, which often leave them after a change to the coast. In open- 
ing up new land by clearing, it is notorious that strangers suffer much 
while the work is going on. Swamps are also unhealthy for strange 
plants. Few cultivated fruit trees can endure inundations for even a 
day or two. Yet, under these conditions, the trees of the forest 
thrive. They have obviously become accustomed to environment 
such as would be dangerous to nearly all others. Is it not possible 
that what is dangerous to a plant is just as injurious to man, unless 
he has protected himself in some way? Also that there may be 
lessons to learn from the way trees have warded off the danger ° 
It is an undoubted fact that the forest giants of Guiana have 
evolved contrivances to prevent the development of low fungi. The 
most common of these is a thick bark containing tannin. This tannin 
is Nature’s great antiseptic. It is found in all the waters of the forest 
and swamp, and accounts for that great difference which exists: 
between the clear brown bog water and that seat of infection the 
stagnant pool. In towns and villages ordinary rain-water, if allowed 
to remain in open trenches, never resembles in its antiseptic properties 
that of the forest. The Indian has gone to the forest and learnt a 
lesson. When suffering from ulcers he scrapes the inner bark of 
some tree and applies it to the sore with most beneficial results. 
Besides this, many other secretions have been developed. One 
of the most extraordinary is, perhaps, the milky juice which dries into 
india-rubber and gutta-percha. It is well-known that the Hevea 
grows only in places that are periodically inundated, and this 
characteristic is also strikingly exemplified in the tree which produces 
balatta, the gutta-percha of Guiana. It may be objected that some of 
the species of Ficus, which have similar juices, do not necessarily 
belong to the swamp, but perhaps their ancestors lived under 
different conditions. These secretions are so evidently fitted for pro- 
tection against water that we can hardly conceive of them in any 
other connection. 
Then there is another large class, the gum-resins and oleo-resins, 
also common in Guiana. Gum animi, the incense gum from the 
hyawa (Icica), and balsam copaiba are the best known examples. 
The species of Copaifera are characterised by their thick bark, from 
which the Indian wood-skin canoes are made, and which are preserved 
